The most common and most likely answer to this crossword clue is the 7 letter word DEFACES
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More clues leading to the result DEFACES
Buddy explains!

The straight part
We know that "This spoils" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this spoils = defaces.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does DEFACES mean?
DEFACES verb- To damage or vandalize something, especially a surface, in a visible or conspicuous manner.
- To void or devalue; to nullify or degrade the face value of.
- (flags) To alter a coat of arms or a flag by adding an element to it.